Warp-knit, weft-insertion (WKWI) fabrics have achieved greater popularity in recent years as lower cost alternatives in end-use applications typically reserved for woven-type fabrics. For example, WKWI fabrics having a "woven-like" appearance have been disclosed in U.S. Pat. No. 4,682,480 as useful as drapery fabrics and for other household and industrial end-use applications. Furthermore, the lower cost and dimensional stability of WKWI fabrics become more desirable (i.e., as compared to woven fabrics) in those end-use applications where the aesthetic appearance of the fabric is not critically important (e.g., as when the fabric is used as a mattress ticking).
The warp yarns in the fabrics disclosed in U.S. Pat. No. 4,682,480 are laid on a face of a substrate and plural weft yarns are then laid over the warp yarns, the warp and weft yarns being held to the substrate by means of plural stitch wales spaced-apart along the warp-wise direction of the fabric. While the use of such a non-woven substrate has proven to be quite satisfactory as a substitute for dense warp and/or tight filling for those fabrics that will subsequently be coated or foam-backed, the "fabric" side (i.e., that side of the fabric on which the warp and weft yarns are laid) is usually a loosely knit weft insertion construction which can only be as loosely knitted as the finishing frame is able to further process. Often therefore, such open constructions are fairly difficult to process because the weft yarns easily slip out since the fabric has no true selvage. In addition with such open constructions, the fabric lacks sufficient opacity, so that when used as a drapery fabric, the esthetic effect of the WKWI yarns is distorted by light passing through the fabric. "Tighter" warp and weft constructions, however, are cost-prohibitive. Therefore, what has been needed is a warp-knit, weft-insertion fabric having improved dimensional stability prior to the application of a coating layer--that is, a fabric whose warp and weft yarn are more dimensionally stable and opaque in an uncoated fabric form.
In accordance with the present invention, a warp-knit, weft-insertion fabric is provided with multiple substrates, the substrates serving to improve the dimensional stability and the opacity of the fabric and thus render it more useful in an uncoated form and create a more expensive-looking, self-lined product. The increased opacity is helpful because it blocks out light through the fabric when used as a drapery fabric, without the need of a separate lining. In one embodiment of the invention, the warp and/or weft yarns are interposed between at least two substrate layers such that the warp stitching yarns hold the two substrates one to another thereby also holding the warp and weft yarns in position relative to one another and to the substrates.
Another embodiment of the invention comprises the warp yarns being interposed between a pair of substrate layers while the weft yarns are laid over one of the substrate layers. The stitching yarns again hold the substrates one to another thereby also holding the warp and weft yarns in position relative to one another and to the substrates.
The multiple substrate layers may also be employed, in accordance with this invention, in a juxtaposed relationship one to another. In this case, increased opacity and dimensional stability as compared to a single substrate layer may be achieved without resorting to traditional foam backing and/or coating materials (although such backings and/or coatings may be provided with the fabrics of this invention if desirable or necessary for the particular end use application in which the fabrics are employed). The combination of different lightweight substrates, one for the inside layer to increase opacity and the other for the outside layer on the back, allows economical variations in the esthetics of self-lined draperies. The substrate combination may also be varied to obtain a softer or firmer hand, as desired. The softer hand would be used for draperies, while a firmer hand would be preferred for a window shade fabric.